Double pole switch with reversible contact structure



W. LANDOW May 24, 1966 DOUBLE POLE SWITCH WITH REVERSIBLE CONTACTSTRUCTURE Filed Nov. 4, 1963 INVENTOR. WALTER LANDOW Robert L. LindgrenUnited States Patent 3,253,092 DOUBLE POLE SWITCH WITH REVERSIBLECONTACT STRUCTURE Walter Landow, Cleveland, Ohio, assignor to The ClarkController Company, Cleveland, Ohio, a corporation of Ohio Filed Nov. 4,1963, Ser. No. 321,093 11 Claims. (Cl. 200-16) This invention relates tocircuit making and breaking apparatus and more particularly to aconvertible pole contact block.

The apparatus of the invention is designed to positively make and breakelectrical circuits during repeated openings and closings of thecontacts thereof over long operating periods. While single pole contactunits may be employed, duplex pole units will produce the greatestflexibility and commercial advantage.

The contact block of the invention offers the advantage of compactness.It may be relatively simply installed and used in connection with AG.and DC. contactors, control relays and timing relays to electricallyinterlock control circuits associated with them.

The normal operative position of the movable contact elements of theunit may be easily reversed to convert the contact and the circuitscontrolled thereby from normally open to normally closed or vice versa.This is accomplished merely by reducing the force being applied to themovable contact element by a resilient biasing means; removing thecontact element from the contact carrier; reversing the position of themovable contact with respect to the resilient biasing means; replacingthe movable contact on the contact carrier; and subjecting the movablecontact to the'force of the biasing means. Other than the contactelement itself and the resilient biasing means, no other part of theapparatus need be disturbed to change or reverse contacts.

The separate contact units of the device are positioned on the moldedhousing thereof in stepped alignment. This permits visual inspection ofthe condition of the contacts during operation from both the front andthe side of the housing, and enables wiring of the contacts from infront of the housing.

The construction of the contact device of the invention also affordssafety features. The contact carrier, which is disposed forreciprocation in the housing, the contacts removably secured thereto,and the resilient biasing means associated with the contacts areconstructed in a manner such that the contacts will assume their normaloperative position even though the externally actuated contact carrieror the contact biasing means become damaged or broken.

Other objects and advantages of the invention shall become more fullyapparent from the following drawings and the detailed descriptionthereof:

FIGURE 1 is a front elevation of the contact device of the inventionhaving a normally open and a normally closed contact;

FIG. 2 is an end view of the device shown in FIG- URE 1;

FIG. 3 is a side elevation of the device;

FIG. 4 is a partial front elevational view of the device of theinvention illustrating the movable contact of the top contact unit ofFIGURE 1 in reversed position thereby converting the unit from normallyclosed to normally open; and

FIG. 5 is a perspective view of a convertible contact of the invention.

As is shown in FIGURE 1, the contact device of the invention comprises ahousing 1 which is molded in one piece from a high impact andelectrically insulating plastic material. Melamine has been found tohave these characteristics and, in addition, has good wearing qualitiesand is resistant to electrical tracking. The one portion of the housingis open and exposes the parts supported thereby while the other portionis closed. The exposed portion of the housing is formed with a top wall2, a pair of generally parallel side walls 3 and 4, a bottom wall 5 anda mid-wall 6 spaced between the top and bottom walls and extending fromthe side walls at an angle generally normal thereto. I

The Walls of housing 1 define an upper chamber 7 and a lower chamber 8.Top wall 2 is formed with a generally vertically extending contactcarrier receiving recess 9. Mid-wall 6 is similarly constructed with anopening 10 which provides communication between chambers 7 and 8; andbottom wall 5, as is shown in FIG. 2, also includes acontact carrierreceiving slot 11. Bottom wall 5 in many of the applications of theinvention is the forwardmost portion of the device and is considered thefront of the device in these instances.

As may be best viewed in FIG. .3, the side walls 3 and 4 of the housingare both formed in steps. The highest step 12 extends from top Wall 2and step 13 extends from step 12. The terminals 14 of two pairs of fixedcontacts 15 are secured to the steps of the side walls. Bottom wall 5,as shown in FIG. 2, is cut away at both its outer ends to fully exposeterminals 14. This provides ready access to terminals 14, particularlyfrom in front of bottom wall 5, but also, almost without regard to theoperative position in which the device is installed.

The fixed contacts 15 extend generally laterally inwardly from terminals14 into the chambers 7 and 8. Each pair of these fixed contacts ispositioned to project laterally into one of the chambers. The contactslie on the same general lateral plane. They are spaced about midwaybetween the lateral walls defining the chamber and the ends thereof arespaced apart in their respective chambers.

A contact carrier 16 is positioned for reciprocal movement in housing 1.As is shown in FIGURE 1, the outermost end of contact carrier 16projects from the housing. The portion of the carrier adjacent this end,as is best seen in FIG. 2, lies in slot 11. From this point, the carrierextends into chamber 8 and between the fixed contacts 15, throughmidwall opening 10, into chamber 7 and between the fixed contactstherein and, finaly, into the recess 9 in top wall 2. The contactcarrier 16 may thereby freely slide vertically in the housing.

To return the contact carrier 16 after it has been moved into contactwith top wall 2, a return spring 17 is positioned in recess 9 betweentop wall 2 and the innermost end of the contact carrier 16. Spring 17 isretained in recess 9 by projection 18 while the end of the springopposite wall 2 engages a centrally located projection 19 formed on theend of carrier 16 to insure proper seating of the spring with respect tothe carrier.

U-shaped snap-fitting nylon retaining clips 20 and 21 are inserted intoslots 22 and 23 of the top wall and bottom wall, respectively, of thehousing. The legs of the clips are formed to engage a snap fittingprovided in the molded body of housing 1, as is shown in FIG. 2. Theseclips serve to maintain the axial position of contact carrier 16 and toprevent other than the generally vertical reciprocating motion of thecarrier with respect to the housing.

The vertical travel of carrier 16 is limited in one direction by topwall 2. Travel in the other direction is limited within upper chamber 7by an annular shoulder 24 provided on carrier 16. Shoulder 24 isdesigned to contact mid-wall 6 and to act as a safety stop for thedownward movement of carrier 16 in the event the carrier should break. Aretaining ring 25 is secured to the lower portion of the carrier 16 inlower chamber '8 and serves to limit the downward movement of thecarrier in this chamber in the same manner as shoulder 24 in chamber 7.A spring 26, which is disposed concentrically over contact carrier 16,is retained within upper chamber 7 and is free to move axially over thecarrier therein. A second spring 27 is positioned In a like manner inlower chamber 8 and may move freely along the axis of carrier 16 withinthe chamber.

Themova'ble contact 28 of the device is clearly shown in the perspectiveview of FIGURE and in operating relation in FIGURES 1 and 4. Theconfiguration of contact 28 is generally U-shaped with lateralextensions 29 projecting in opposite directions from the legs of the U.A spring seating cup member 30 is secured to the portion of contact 28between the legs of the U. Both the movable contact 28 and cup member 30have a generally rectangular notch 31 cut into an edge thereof. Thisnotch conforms to the shape of constricted segments 32 and 33 of contactcarrier 16 which are respectively located in upper chamber 7. and lowerchamber 8.

In order to permit the proper alignment of the movable contacts 28 withtheir respective fixed contacts 15, constricted segment 32 of carrier 16in upper chamber 7 is located on a plane above that of the constrictedsegment 33 in lower chamber 8. This relationship is illustrated in FIG.2. This positioning acts to align the movable contact 28 in chamber 7 atthe higher level required by the elevated location of fixed contacts 15therein while contact 28 in chamber 8 is carried at the required lowerlevel. It also serves, as can be seen in FIG. 2, to permit easier visualobservation of the condition of the contacts and to facilitate thewiring thereof.

Each of the fixed contacts 15, which is secured to the housing, isprovided with a pair of contact buttons 34 which are bonded to oppositesurfaces of their respective contacts. Contact buttons 35 are bonded toextensions 29 of movable contact 28. To obtain a normally closedcircuit, as is shown in chamber 7 of FIGURE 1, spring 26 is manuallymoved using the point of a pencil or a screwdriver to the upperextremity of chamber 7 and firmly against a seat provided in top wall 2.The notch 31 of movable contact 28 is inserted into the upperconstricted segment 32 of carrier 16. The contact buttons 35 of themovable contact 28 are faced to establish electrical contact with theupper fixed contact buttons 34 of the housing. When spring 26 isreleased, it becomes seated on cup member 30, and its position ismaintained thereby. The spring, which is now seated at one end againsttop wall 2 and at the other against cup member 30 secured to movablecontact 28, acts to maintain the contacts in their normal operativeclosed position.

a When the contacts of chamber 7 are in their normally closed condition,a mechanical or electro-mechanical force exerted upon the outermost endof contact carrier 16 will move the contact carrier vertically upward.The notch portion 31 of contact 28 will slide a short distance along theconstricted segment 32 of the carrier. The annular shoulder 24 of thecarrier will then be brought into engagement with the portion of movablecontact 28 beneath cup member 30 and will overcome the forces of springs17 and 26 to break electrical contact. Upon release of the force exertedagainst carrier 16, the combined action of return spring 17 and spring26 will restore the movable contact to its normally closed position.

To reverse the normal operative position of the movable contact 28 ofupper chamber 7 with respect to the fixed contacts thereof, as is shownin FIG. 4, the spring pressure on cup member 30 is released by manuallycompressing spring 26 against top wall 2. Contact 28 can then beextracted from chamber 7 in a direction generally perpendicular to thelongitudinal axis of carrier 16. Spring 26 is released and slid alongthe carrier to the opposite end of the upper chamber 7 Where it engagesa seat formed in annular shoulder 24. The spring is then manuallycompressed against this seat to expose constricted segment 32 of thecarrier. The notch 31 of movable contact 28 is inserted over theconstricted segment of carrier 16 and at the end of the segment oppositewhich it is inserted for the normally closed contact. Contact 28 isinserted in a direction which is generally perpendicular to the axis ofthe carrier. The cup member 30 of the contact, upon installation, facesthe end of spring 26 opposite shoulder 24, and contact buttons 35 facethe bottom buttons 34 of fixed contacts 15. Spring 26 is then releasedand becomes securely seated upon the cup member and forces the contactmember 28 into firm engagement with the portion of carrier 16 abuttingthe upper end of constricted segment 32. Reversal of the normaloperative position of the contact is thereby accomplished by disturbingonly spring 26 and contact 28, and only the contact is removed from thehousing.

When the contact carrier is actuated to move upwardly, the normally opencontacts shown in FIG. 4 are brought into electrical contact. Theextensions 29 of contact 28 and the contact buttons 35 attached theretohave been found to produce best results when they are set at an angle ofabout 2 from horizontal. As the movable contact engages the fixedcontacts, constricted segment 32 slides through notch 31. This causesthe spring 26 to act in conjunction with the angular disposition ofextensions 29 to produce a positive Wiping action on the contacts tothereby insure the reliable establishment of an electrical circuitthrough the contacts upon their closing. Spring 17 acts to return themovable contact 28 to its normal open position when the carrier isreleased.

The movable contact of the contact unit in lower chamber 8 may beinitially positioned in normally open or normally closed relation to thefixed contacts therein. It may be reversed from one position to anotherat will and in the manner prescribed above for the contact unit ofchamber 7.

When the apparatus of the invention is to be connected into a circuit,the screws of terminals 14 are loosened. This provides wire access tothe area between pressure member 36 and the housing. Pressure member 36is usually fabricated as an L-shaped stamped piece. It has been found tobe highly advantageous in connecting the wires of'a circuit to terminals14 to form member 36 with a centrally located indentation 37at the pointof intersection of the legs of the L. This produces a ridge on theinwardly facing surface of member 36 which acts to engage a wire leadinserted between the member and the housing and to force it into firmelectrical contact with the terminal screw. Positive electrical contactis thereby assured.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. A contact device comprising a molded insulating housing open on oneside, the housing being formed with first and second chambers, thechambers being separated by a common wall, the first chamber having anend wall, a pair of side walls and the common wall, the second chamberhaving side walls, an end wall and the common wall, a portion of theside walls of the first chamber being formed in elevated relation towardthe open side of the housing with respect to the side walls of thesecond chamber, the end wall of the second chamber and the common wallhaving openings therein to receive a contact carrier, the end Wall ofthe first chamber having a recess in alignement with the openings topermit the reciprocal motion therein of a contact carrier, a fixedcontact secured at one end to the elevated portion of a side wall of thefirst chamber and another fixed contact secured in like manner to theother side wall and each fixed contact extending laterally therefrominto the first chamber, fixed contacts secured to the side walls of thesecond chamber and extending therein, the fixed contacts of the secondchamber being positioned at a level below that of the fixed contacts ofthe first chamber thereby permitting the connection of both groups ofcontacts in circuits from directly in front of the end wall of thesecond chamber, a contact carrier slidably disposed in the openings andthe recess and extending between the fixed contacts in the first andsecond chambers, a pair of contact bars connected to the contactcarrier, one of the bars being positioned for electrical contact withthe fixed contacts of the first chamber and the other bar beingpositioned for electrical contact with the fixed contacts of the secondchamber, and operating means associated with the contact carrier toproduce the reciprocal motion thereof with respect to the 3. The contactdevice of claim 1 wherein the opening, in the end wall of the secondchamber and the recess in the end wall of the'first chamber are providedwith means to substantially prevent the movement of the contact carrierin other than the direction of the longi' tudinal axis thereof.

4. The contact device of claim 1 wherein resilient biasing means aredisposed in the recess of the end wall of the first chamber between theend wall and the end of the contact carrier projecting therein to returnthe contact carrier and the contact bars to their normal positions uponinactivation of the operating means.

5. The contact device of claim 1 wherein the contact bar in the firstchamber is positioned at a plane on the contact carrier above that ofthe contact bar in the second chamber to permit visual observation froma point in front of the end wall of the second chamber of the conditionof the fixed contacts and contact bars, and circuit connection meansdisposed to the side of the contacts and generally in the plane of thecorresponding contact bar to permit simple installation of circuit leadsfrom in front of the end wall.

6. A contact apparatus comprising an insulating housing, the housinghaving a chamber closed on one side and open on the other and having afirst end wall, a second end wall and a pair of side walls, the firstend wall being formed with a recess and the second end wall having anopening in alignment with the recess to align and guide the reciprocalmovement of a contact carrier therebetween, fixed electrical contactssecured to the side walls and extending into the chamber and spaced fromthe end walls thereof, a contact carrier positioned in the chamberbetween the fixed contacts, the contact carrier extending into therecess of the first end wall and through the opening in the second endwall and adapted for reciprocal motion in the chamber, a contact barslidably disposed upon the contact carrier and removable therefrom in adirection generally normal to the longitudinal axis of the contactcarrier and through the open side of the housing without removing thecontact carrier from the chamber, resilient biasing means positioned onthe contact carrier between the contact bar and an end wall to maintainthe contact bar in one operative position with respect to the fixedcontacts and to yieldably oppose the movement of the contact carrierwhen actuated to change the operative position of the contact bar.

7. The contact apparatus of'claim 6 wherein the fixed contacts thereofare provided with terminal elements adjacent the side walls of thehousing, the first terminal element having means thereon for forcing thelead of an electrical circuit into positive electrical contact with thefixed contact, the-second terminal element having means for biasing thefirst element against an electrical lead.

8. The contact apparatus of claim 6 including resilient means in therecess to resiliently return the contact carrier from one operativeposition to another.

9. A contact apparatus comprising an insulating housing, the housinghaving a chamber closed on one side and open on the other and having afirst end wall, a second end wall and a pair of side walls, the firstend wall being formed with a recess and the second end wall having anopening in alignment with the recess to align and guide the reciprocalmovement of a contact carrier therebetween, fixed electrical contactssecured to the side walls and extending into the chamber and spaced fromthe end walls thereof, a contact carrier positioned in the chamberbetween the fixed contacts, the contact carrier extending into therecess of the first end wall and through the opening in the second endwall and adapted for reciprocal motion in the chamber, a contact barhaving a centrally located edge notch and slidably mating with thecontact carrier and removable therefrom in a direction generally normalto the longitudinal axis of the contact carrier and through the openside of the housing without removing the contact carrier from thechamber, and resilient biasing means disposed for axial sliding movementon the contact carrier between the contact bar and an end wall and in amanner such that the biasing means cannot be removed from the carrierwithout withdrawal of the carrier from the chamber, the resilientbiasing means acting to maintain the contact bar in a normal operativeposition with respect to the fixed contacts and to yieldably oppose themovement of the contact bar when actuated to change the normal operativeposition thereof, the normal operative position of the contact bar beingreversible with respect to the fixed contacts by removing the bar fromthe carrier in a direction generally normal to the longitudinal axis ofthe carrier, sliding the biasing means on the carrier in a directionopposite its previous position and replacing the bar on the carrier andin contact with the opposite end of the biasing means.

10. The contact apparatus of claim 9 including means on the contactcarrier to prevent the complete longitudinal withdrawal of the carrierfrom the chamber and releasable retaining clip means releasably securedto the open side of the housing and about the carrier to secure thecontact carrier from withdrawal from the chamber in a direction normalto the longitudinal axis of the carrier,

the longitudinal withdrawal preventing means associated with the carrierserving to prevent the accidental removal of the resilient biasing meansand the contact carrier from the chamber.

11. An electrical terminal for connecting electrical circuits comprisingan electrical contact member, a plate having a pair of intersectinglegs, the planes of intersection thereof defining an angle of less thanand generally having an L-shaped appearance, one of the legs having asurface generally conforming to a surface of the contact member andaligned with the contact member with the opposite leg extending over thecontact member, the plate being formed with an internal ridge connectingthe intersecting legs thereof, and a threaded pressure member extendingthrough the surface of the plate conforming to the contact member andthreaded into the contact member, the ridge of the plate acting to forcean electrical lead disposed between the plate and the contact memberinto positive electrical contact with the member upon the application ofpressure to the plate 3,045,092 7/1962 Bundy 20016 X by the threadedpressure member. 3 047 33 7 19 2, Aushermam References Cited by theExaminer 3,170,054 2/ 1965 Lawrence et a1. 20016 X UNITED STATES PATENTS5 2,811,617 10/1957 Townsend. KATHLEEN H. CLAFFY, Przmury Exammer.

3,018,338 1/1962 Mullen et a1. 200 -16 JAMES R. SCOTT, AssistantExaminer.

6. A CONTACT APPARATUS COMPRISING AN INSULATED HOUSING, THE HOUSINGHAVING A CHAMBER CLOSED ON ONE SIDE AND OPEN ON THE OTHER AND HAVING AFIRST END WALL, A SECOND END WALL AND A PAIR OF SIDE WALLS, THE FIRSTEND WALL BEING FORMED WITH A RECESS AND THE SECOND END WALL HAVING ANOPENING IN ALIGNMENT WITH THE RECESS TO ALIGN AND GUIDE THE RECIPROCALMOVEMENT OF A CONTACT CARRIER THEREBETWEEN, FIXED ELECTRICAL CONTACTSSECURED TO THE SIDE WALLS AND EXTENDING INTO THE CHAMBER AND SPACED FROMTHE END WALLS THEREOF, A CONTACT CARRIER POSITIONED IN THE CHAMBERBETWEEN THE FIXED CONTACTS, THE CONTACT CARRIER EXTENDING INTO THERECESS OF THE FIRST END WALL AND THROUGH THE OPENING IN THE SECOND ENDWALL AND ADAPTED FOR RE-